VEGA Capacitive electrodes EL 4 … 20 mA - Compact - Manual (Page 19)

Capacitive electrodes EL 4 … 20 mA - Compact 19
22652-EN-020809
Mounting
Metal vessel
Make sure that the mechanical connection of
the electrode to the vessel is electrically con-
ductive in order to ensure sufficient ground-
ing.
Use conductive seals such as e.g. copper,
lead etc. Insulating measures, such as cover-
ing the thread with Teflon tape, can interrupt
the necessary electrical connection. In such a
case, use the earth terminal on the housing to
connect the electrode to the vessel wall.
Non-conductive vessels
In non-conductive vessels, e.g. plastic tanks,
the second pole of the capacitor must be
provided separately, e.g. in the form of a
concentric tube or by the use of a double rod
electrode.
When using a standard electrode, a suitable
grounding surface is necessary. Provide
therefore the largest possible grounding sur-
face, e.g. wire braiding laminated into the
vessel wall or metal foil glued to the vessel.
Connect the grounding surface to the ground
terminal on the housing.
Rod electrode
Mount the rod electrode such that the elec-
trode protrudes into the vessel. When mount-
ing in a tube or a socket, material buildup
which deters the measurement can form. This
is particularly the case with viscous or adhe-
sive mediums.
Cable electrodes in solids
Depending on the type of solid, the filling
method and its location, the cable electrode
may “float“ in spite of the gravity weight. The
electrode (cable) is pushed by the solid
against the vessel wall or to the surface, thus
causing incorrect measured values. This
should be avoided during continuous meas-
urement.
If this happens, use a fixing weight or insulator
to secure the cable electrode (fig. 2.4)
When securing the cable electrode, avoid high
tensile forces. An appropriate fixing spring
which prevents cable overload can be found
in our price list.
Fig. 2.4 Cable electrode in solids